Air speed switch



AIR SPEED SWITCH Filed Jan. 29, 1931 ['11 Venfor Patented Sept. 20, 1932UNITED STATES 'IPIEBBE motor. or

vmcrmx. salmon ABBYEED SWITCH Application filed January 29, 1981, SerialNo. 518,188, and in France February 11, 1980.

The present invention relates to an automatic indicator, destined tosignal to the pilot of an aeroplane, either a loss, or an excess ofspeed. In the first case, the predetermined minimum speed limit, inspite of the real loss of speed, is yet great enough to allow the pilotto effect the desired operation to excite and restore the aeroplane toits normal speed.

In the second case, the aviator can immediately diminish the speed ofhis aeroplane by operating on the throttle or by diminishing theexcitation.

In the two casesthe signalling can be effected by means of audible orluminous warnings. In the case of loss of speed, the pilot w1ll bewarned for example by means of a warning horn and in the other case bthe intermediary of a lamp which will lig t at the desired moment. Thewarning horn could even be employed as an indicator in the two cases.

The characteristics of the invention resides in the employment of ablade of appropriate shape mounted by means of an arm on a stretchedpiano wire and the torsion couple of which is preferably regulatable.According to the speed of the aeroplane, the streams of air operate onthis blade which is located in a position perpendicular to the line offlight so that it is displaced and turns with the piano wire which isthus subjected to a torsion strain. If the speed of the aeroplanediminishes to its critical point the arm of the blade brought towards te front causes, by means of appropriate contacts, the closing of acircuit on the audible indicator. If on the contrary, there is an excessof speed, the blade acts on an intermediatespring with regulatabletension which allows the closing of the corresponding circuit on theluminous signal at the desired moment, or even on the warning horn.

The annexed drawing represents by way of example, a method of carryingthe invention into-effect.

In this latter,

Fig. 1 shows a view in elevation the apparatus partly in section.

Fig. 2 is a lateral view according'to' Fig. 1

grooves correspondingly disposed in each plate.

showing the arrangement of the electric contacts.

Fig. 3 is a lateral view of the regulating device destined" to signal tothe pilot the excess of speed, and a Fig. 4 is a plan view on line A, AFig. 1 partially in section according to Fig. 1.

The indicator is constituted by a tube 1, provided at its upper partwitha cap 2 carrying a locking piece 3 destined for the fixing of the pianowire 4. This wire traverses the tube axially and is attached to thefixing device 5 mounted in a sheath 6 able to turn on the tube-1 and thechamfered extremity 7 of which carries a series of graduations, in.

kilometres per hour. The piano wire 4 traverses a guiding plug 8 thethreaded tail 9 of which is provided with a nut 10 with a lock-nut 11allowing the wire to stretch on coming to rest by looking on the fixingpiece 5. It is easy to understand that by turning the sheath 6 in onedirection or the other, one exercises on the piano wire a certaintorsion to the right or left, the an le of which is fixed by thegraduations of tie chamfered part and the datum line 0 marked on thetube 1. In the middle of the tube 1 is disposed an opening 12 allowingthe passage of the arm 13 made in one with the blade 14. This openingserves at the same time for the mounting of the blade 14 on the pianowire 4. The arm 13 of the blade is terminated by a rectangular plate 15corresponding to a plate 15 of the same form made in one with the arm 16of the contact carrier 16". These two plates are assembled by meansof-four screws. Between.

these two lates 15 and 15' is locked the piano wire 4 w ich is heldbetween two small The contact carrier 16 is provided with two contactpieces 17 and 18, one placed above and the other below and disposedopposite the contact (pieces 19 and 20 which are fixed and mounte onmetallic supports fitted in an ebonite element E fixed appropriatemanner.

The contact piece 20 serves to close the cir- 'on the tube 1 in an cuitto signal the excess of speed whilst the I contact piece 19 closes thecircuit to indicate the loss of speed.

When the apparatus is only used to indicate t the loss of speed, theblade 14, on which act the streams of air, abuts against a fixed stopnot shown, and maintains itself thus during the whole period of normalflight. If a loss of speed occurs, the blade is brought towards thefront under the eifect of the torsion strain of the piano wire and theelectric circuit is then closed by the contacts 17 and 19 on the audiblesignalling apparatus, a suitable battery being interposed in thecircuit.

If the apparatus is destined at the same time to signal any excess speedof the apparatus, the blade 14, at the time of normal running, andinfluenced by the streams of air is adapted to rest against theextremity of a flat spring 21 (Fig. 3) held at 23 and mounted on asupport 22. Between the arms of this support is fixed a threaded rod 24in the threads of which can be displaced a slide 25 the finger 26 ofwhich is adapted to abut against the flat sprin 21. By makingsthethreaded rod 24 turn iy means of the regulating screw 27, the slide isdisplaced and it is thus possible to make the position of rest of thefinger 26 vary in order to increase or diminish the resistance of thespring. One can thus regulate the moment of closing the electric circuitto indicate excess speed to the pilot.

The apparatus thus permits automatic signalling to the pilot of all lossor excess of speed. by the intermediary of two different signallingsystems or even by employing the same signalling device. It can beregulated in a very sensitive manner and its functioning will be verysure. Binding posts or terminals 28, 29 and 30 are disposed so as toallow an easy connection to the battery and the signalling apparatus.One of the terminals 28 will be connected to the battery and the warninghorn and the circuit closed on the terminal 30 connected by a wire 31soldered to the plate 15 in the line of the axis. The terminal 29will-also be connected to the terminal 30 with connection on the batteryand the signalling lamp or the warning horn. In no case, does theelectric current traverse the piano wire.

To give to the a paratus a perfect tightness and to secure the contactsfrom the action of the streams of air, all the mechanism is isolated ina shaped cover fixed on the tube 1 by means of screws.

It is to be understood that the apparatus is only described by way ofexample, its form and construction are adapted to be modified and variedat will without at all changing the principle underlying the invention,a princi 1e 0 early set out in the present text.

what I claim and desire to secure by Letters Patent of the United Statesof America is An automatic indicator device for aircraft comprising atubular member having a stretched piano wire extendin through theinterior thereof, one end of the wire being fixed to one end of thetubular member, the other end of the wire being fixed to a sheathmounted to turn and be retained in any desired position on the other endof the tubular member, a blade attached to and supported by the wire,said blade extending exteriorly of the tubular member and havingassociated therewith electrical contacting devices, means to regulatethe moment of closing of the electrical contacting devices, said meansincluding a fiatspring, one end of which is connected to the tubularmember and the other end of which is adapted 'to abut against the blade,and a slide mounted upon a screw threaded rod supported by the tubularmember, said slide having a finger abutting against the flat spring, forthe purposes set forth.

In witness whereof I afiix my signature. PIERRE MAULDE.

